OPS+

OPS+: This is an adjusted version of OPS (which is On-Base% + Slugging%). In recent years, OPS has started to replace Batting Average as the go-to “rate” statistic. Until recently, every televised baseball game would show a batter’s batting average, home runs and RBI. Batting average (as a rate stat) is easy to understand. Today, some telecasts will also show a player’s On-base% or their OPS. What OPS+ does is adjust the OPS of each player to account for ballpark effects and also the overall hitting-friendliness of the era in which the player appeared. Common sense tells us that a member of the Colorado Rockies has a hitting advantage over a member of the San Diego Padres. It’s the mile high air vs the marine layer. In addition, certain changes in the history of the game made it easier or more difficult to hit. Whether its ballpark sizes, the height of the mound or the core of the ball itself, every year is different. OPS+ put it on the same playing field.

OPS+ also serves to make OPS a more easily understood statistic. As baseball fans, we’re conditioned to know that a .300 batting average is good and a .225 average is bad. But do we all intuitively know what’s a good number for OPS? Future generations of baseball fans undoubtedly will but OPS+ sets 100 as “average.” Therefore, if you’re above 100, your OPS is above average, if it’s lower, you’re below average.

One limitation of OPS+ should be noted. It does not account for platoon splits within a particular ballpark. So, to use the best example, all three incarnations of Yankee Stadium have featured a short right-field fence. The first two versions included massive gaps in left-center field. Therefore, the right-handed hitting Joe DiMaggio’s still-excellent career 155 OPS+ almost certainly understates his value. The ballpark calculation for OPS+ covers just the ballpark trends as a whole, not as it relates to left-handed hitters vs right-handed hitters. DiMaggio’s career was shortened by his military service in World War II but still, his career total of 361 home runs was deflated by Yankee Stadium (he hit 213 taters in road games, just 148 at home).